feynlag.pheno.particles.DiracParticle

class feynlag.pheno.particles.DiracParticle(particle, left, right, mass, color=1, antiparticle=None)

One physical Dirac fermion, assembled from its two Weyl legs.

Parameters:

• particle (Symbol) – the particle symbol (a str is promoted to a Symbol), e.g. 'b'.

• left (IndexedBase) – the left-handed Weyl leg base — the IndexedBase returned by fermion.components[k] (e.g. QL.components[1] for the down-type member of a quark doublet).

• right (IndexedBase) – the right-handed Weyl leg base (e.g. bR.components[0]).

• mass (Expr) – the physical mass (symbol or number).

• color (int) – colour multiplicity $N_c$ — 3 for a quark, 1 (default) for a lepton. Applied once per channel by the calculator, so no per-leg double counting is possible.

• antiparticle (Symbol) – the antiparticle symbol; defaults to Symbol(f"{name}bar").

The bar legs (bar_left/bar_right) are looked up from the bar_partner() registry, not supplied.

__init__(particle, left, right, mass, color=1, antiparticle=None)

Parameters:

• particle (Symbol)

• left (IndexedBase)

• right (IndexedBase)

• mass (Expr)

• color (int)

• antiparticle (Symbol)

Return type:

None

Methods

__init__(particle, left, right, mass[, ...])
colors()	{particle: N_c, antiparticle: N_c}.
masses()	{particle: mass, antiparticle: mass}.
particle_map()	{weyl_leg_base: physical_symbol} for this particle.

Attributes

antiparticle
bar_left	The bar leg paired with left (from bar_partner()).
bar_right	The bar leg paired with right (from bar_partner()).
color
particle
left
right
mass